fix(cli): fix crash when exiting Metro server in 0.83

[tido64]

Description

Exiting the Metro server crashes starting with 0.83:

% yarn start

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                Welcome to Metro v0.83.0
              Fast - Scalable - Integrated


┃ Open developer menu                  D
┃ Open debugger                        J
┃ Show bundler address QR code         Q
┃ Reload the app                       R
┠───────────────────────────────────────
┃ Show this help message               H
┃ Quit                            Ctrl-C

info Exiting...
node:internal/readline/emitKeypressEvents:74
            throw err;
            ^

TypeError: server.close is not a function
    at process.<anonymous> (/~/node_modules/@rnx-kit/cli/lib/serve/keyboard.js:75:16)
    at process.emit (node:events:518:28)
    at ReadStream.<anonymous> (/~/node_modules/@rnx-kit/cli/lib/serve/keyboard.js:90:29)
    at ReadStream.emit (node:events:518:28)
    at emitKeys (node:internal/readline/utils:370:14)
    at emitKeys.next (<anonymous>)
    at ReadStream.onData (node:internal/readline/emitKeypressEvents:64:36)
    at ReadStream.emit (node:events:518:28)
    at addChunk (node:internal/streams/readable:561:12)
    at readableAddChunkPushByteMode (node:internal/streams/readable:512:3)

Node.js v22.15.0

Test plan

n/a